Motor control

The discipline of Motor Control is the study of human movement and the systems that control it under normal and pathological conditions.
Depends upon -
Environmental result of the movement (Outcome)
Movement pattern
Neuromotor processes underlying movement

1. Theories of motor

controlDr. Maheshwari Harishchandre
Assistant Professor
M.P.Th (Neurosciences)
DVVPF College of Physiotherapy, Ahmednagar

2. Objectives
What is motor control.
Different theories of motor control
Clinical implications.
Limitations.

3. Motor Control
Defn – The ability of regulate or direct the
mechanisms essential to movement.
Why is it necessary to know?
Movement emerges from three factors -

5. Individual – Action, Perception, Cognition
Task – Stability, Mobility, Manipulation
Environment – Regulatory, Nonregulatory

6. Description
The discipline of Motor Control is the study of human
movement and the systems that control it under
normal and pathological conditions.
Depends upon -
Environmental result of the movement (Outcome)
Movement pattern
Neuromotor processes underlying movement

7. A theory of motor control is a group of
abstract ideas about the control of
movement.
A theory is a set interconnected
statements that describe unobservable
structures or processes & relate them to
each other & to observable events.

8. Theories of Motor control
Reflex theory
Hierarchical theory
Complex systems theory
Motor Programming Theories
Systems Theory.
Ecological Theory

9. Reflex Theory
Reflex Theory (Charles Sherrington)
Complex behavior (movement) is
controlled by a series of chained
reflexes

11. •Sir Charles Sherrington, the integrative Sir Charles Sherrington, the integrative
action of the nervous system (1906) action of the nervous system (1906)
•This is based on the observation that This is based on the observation that
monkeys were unable to lift their arm after monkeys were unable to lift their arm after
resection of resection of one side one side of dorsal root of dorsal root
ganglia. ganglia.  Therefore, sensory inputs must Therefore, sensory inputs must
be essential in initiating movements.be essential in initiating movements.

12. Clinical Implications
If the chained or compounded reflexes are
the basis of functional movement, clinical
strategies designed to test the reflexes
should allow the therapist to predict
functions.
Patients movement behaviors would be
interpreted in terms of presence or
absence of controlling reflexes.

13. Limitations of Reflex TheoryLimitations of Reflex Theory
•Unable to explainUnable to explain
–Spontaneous and voluntary movementsSpontaneous and voluntary movements
–Movement can occur without a sensory Movement can occur without a sensory
stimulus ex- Fast sequential stimulus ex- Fast sequential
movements, e.g. typing movements, e.g. typing
–A single stimulus can trigger various A single stimulus can trigger various
responses (reflexes can be modulated) responses (reflexes can be modulated)

14. Hierarchical Theory
Hierarchical Theory
(H Jackson 1930s)
Movement is
controlled by a
system consisting of
3 levels with a rigid
top down
organization
Higher centers
control lower
centers

15. •Higher centers are always control lower Higher centers are always control lower
centerscenters
•Higher centers inhibit the reflexes Higher centers inhibit the reflexes
controlled by lower centerscontrolled by lower centers
•Reflexes controlled by lower centers are Reflexes controlled by lower centers are
present only when higher centers are present only when higher centers are
damageddamaged

16. This theory suggest that motor control This theory suggest that motor control
emerges from reflexes that are nested emerges from reflexes that are nested
within hierarchically organized levels of within hierarchically organized levels of
the CNS.the CNS.
–A child’s capacity to sit, stand, and walk A child’s capacity to sit, stand, and walk
is related to the progressive emergence is related to the progressive emergence
and disappearance of reflexesand disappearance of reflexes
–Brain stem reflexes (associated with Brain stem reflexes (associated with
head control) emerge before midbrain head control) emerge before midbrain
reflexes (associated with trunk control)reflexes (associated with trunk control)

17. Hierarchical TheoryHierarchical Theory

18. Current Concepts Related to Current Concepts Related to
Hierarchical TheoryHierarchical Theory

Each level of the motor system can act Each level of the motor system can act
on other levels on other levels

Reflexes are not considered the soul Reflexes are not considered the soul
determinant of motor control but only as determinant of motor control but only as
one of many processes important to the one of many processes important to the
generation and control of movement.generation and control of movement.

19. Clinical Implications of Clinical Implications of
Hierarchical TheoryHierarchical Theory
““When the influence of higher centers is temporarily or When the influence of higher centers is temporarily or
permanently interfered with, normal reflexes become permanently interfered with, normal reflexes become
exaggerated and so called pathological reflexes exaggerated and so called pathological reflexes
appear” Brunnstrom, appear” Brunnstrom,
““The release of motor responses integrated at lower The release of motor responses integrated at lower
levels from restraining, influences of higher center, levels from restraining, influences of higher center,
especially that of the cortex, leads to abnormal postural especially that of the cortex, leads to abnormal postural
reflex activity”…Bobath, 1965 reflex activity”…Bobath, 1965

20. Limitations of Hierarchical Limitations of Hierarchical
TheoryTheory
•Environment and other non-CNS factors Environment and other non-CNS factors
can affect movement, e.g. Thelen’s can affect movement, e.g. Thelen’s
experiments showed that baby’s stepping experiments showed that baby’s stepping
response re-emerges with body weight response re-emerges with body weight
support support
•Normal adults exhibit lower level reflexes, Normal adults exhibit lower level reflexes,
e.g. flexor withdrawale.g. flexor withdrawal

21. –Many studies found that movement is Many studies found that movement is
possible even possible even in the absence of stimuli in the absence of stimuli
or sensory inputor sensory input
–Sensory inputs are not required to Sensory inputs are not required to
produce a movement but they are produce a movement but they are
important in important in adapting and modulating adapting and modulating
the movement the movement
Motor Programming TheoriesMotor Programming Theories

22. Motor Programming TheoriesMotor Programming Theories
•Motor programs areMotor programs are
–Hardwired and stereotyped neural connections such Hardwired and stereotyped neural connections such
as central pattern generators (CPGs)as central pattern generators (CPGs)
–Abstract rules for generating movements at the higher Abstract rules for generating movements at the higher
levellevel
•Motor program can be activated by sensory stimuli or by Motor program can be activated by sensory stimuli or by
central processescentral processes

23. Clinical Implications of Clinical Implications of
Motor Programming TheoriesMotor Programming Theories
•Movement problems are caused by abnormal Movement problems are caused by abnormal
CPGs or higher level motor programs CPGs or higher level motor programs
•It is important to help patients relearn the It is important to help patients relearn the
correct rules for actioncorrect rules for action
•Focus on Focus on retraining movements that are retraining movements that are
critical to a functional taskcritical to a functional task, not just specific , not just specific
muscles in isolationmuscles in isolation

24. Limitations of Motor Limitations of Motor
Programming TheoriesProgramming Theories
•Does not consider that the nervous system must deal Does not consider that the nervous system must deal
with both musculoskeletal and environmental with both musculoskeletal and environmental
variables to produce movementsvariables to produce movements
–e.g. identical neural commands to elbow flexors e.g. identical neural commands to elbow flexors
can produce different movements depending on can produce different movements depending on
the initial position of the arm and the force of the initial position of the arm and the force of
gravitygravity

25. Systems Theory:Systems Theory:
•How does the CNS select a solution from an How does the CNS select a solution from an
infinite number of possibilities for a task?infinite number of possibilities for a task?
•SolutionSolution
–Higher levels activate lower levels while Higher levels activate lower levels while
lower levels activate lower levels activate synergiessynergies, i.e. groups of , i.e. groups of
muscles that are constrained to act together muscles that are constrained to act together
as a unitas a unit

26. •Viewed body as a mechanical system, Viewed body as a mechanical system,
involving the interaction between mass, involving the interaction between mass,
external force (e.g. gravity), internal forceexternal force (e.g. gravity), internal force
•““Coordination Coordination of movement is the process of movement is the process
of mastering the redundant degrees of of mastering the redundant degrees of
freedom of the moving organism” freedom of the moving organism”
(Bernstein, 1967)(Bernstein, 1967)

27. Systems Theory: Latash’s Systems Theory: Latash’s
Principle of AbundancePrinciple of Abundance
•Synergy Synergy is a is a task-specifictask-specific covariation of covariation of elemental elemental
variablevariables with the purpose to s with the purpose to stabilize a stabilize a
performance performance variable, i.e. minimize errors of a variable, i.e. minimize errors of a
performance variable performance variable
–Reaching: joint rotation angleReaching: joint rotation angle stabilize hand stabilize hand
position position
–Grasping: individual finger forceGrasping: individual finger force stabilize total stabilize total
grasp forcegrasp force
–Standing stability: postural muscle activation Standing stability: postural muscle activation 
stabilize COPstabilize COP

28. Clinical Implications of Systems Clinical Implications of Systems
TheoryTheory
•Body is a mechanical system. Consider Body is a mechanical system. Consider
musculoskeletal factors underlying a patient’s musculoskeletal factors underlying a patient’s
movement problemmovement problem
•Changes in movements may not necessarily result Changes in movements may not necessarily result
from neural changes, e.g. faster vs. slow gait, speed from neural changes, e.g. faster vs. slow gait, speed
during sit to standduring sit to stand
•Encourage the patient to explore variable Encourage the patient to explore variable
movementsmovements

29. Dynamic Systems Theory: Dynamic Systems Theory:
Principle of Self-OrganizationPrinciple of Self-Organization
•Movement emerges as a result of interacting Movement emerges as a result of interacting
elements. No needs for specific neural elements. No needs for specific neural
commands or motor programs.commands or motor programs.
•Variability of movement is normal. Optimal Variability of movement is normal. Optimal
amount of variability allows for flexible, adaptive amount of variability allows for flexible, adaptive
strategies to meet the environmental demandstrategies to meet the environmental demand

30. Clinical Implications
This theory helps in understanding the
physical and dynamic properties of human
body , we can make use of these
properties in helping the patients to regain
motor control

31. Limitation of Systems TheoryLimitation of Systems Theory
•Nervous system is fairly unimportantNervous system is fairly unimportant

32. Ecological Theory: Ecological Theory:
•Action is specific to the task goal and the Action is specific to the task goal and the
environmentenvironment
•Perceptual information of the Perceptual information of the
environmental factors relevant to the task environmental factors relevant to the task
goal is necessary to guide the action goal is necessary to guide the action
•Limitations:Limitations:
–↓ ↓ emphasis on nervous systememphasis on nervous system

33. Clinical Implications of Clinical Implications of
Ecological TheoryEcological Theory
•Individual is an active explorer of the Individual is an active explorer of the
environment for learningenvironment for learning
•Individual discovers multiple ways to solve Individual discovers multiple ways to solve
movement problems in environmentmovement problems in environment
•Fundamental to the play-based therapy for Fundamental to the play-based therapy for
pediatric patientspediatric patients